Magneto-optical recording and reproducing system

Abstract

A magneto-optical recording and reproducing apparatus for recording information on a recording medium made of a magneto-optical recording material. The apparatus is provided with at least two lasers for carrying out simultaneously a combination of two functions of the apparatus such as recording-reproducing or reproducing-erasing or erasing-recording functions. The recording and erasing is effected optically by independent light beams. Provision is made for recording and erasing the information by light beam and by use of an application of magnetic fields of different coercive values. The lasers are modulated or not independently and an optical system is provided through which the write-in and readout takes place and focusing is in response to the reflected light from the record on the recording medium.

What we claim is: 
     
       1. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material comprising; an optical system for applying a plurality of light beams on said recording medium for radiating the recording medium with incident radiation at a plurality of irradiated positions; drive means for driving the optical system and the recording medium relatively to each other for shifting positions on the recording medium irradiated by said light beams; mode magnetic field generating means disposed for generating coercive fields of different coercive values applied to said recording medium forwardly and rearwardly of some of said irradiated positions; photo-detecting means for detecting reflected light from said medium; control means for effectively controlling said optical system, said drive means, said mode magnetic field generating means and said photo-detecting means for effecting selectively recording-reproducing concurrently or reproducing-erasing concurrently or erasing-recording of said information of said recording medium.   
     
     
       2. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 1, in which said recording medium is a flim, and in which a magnetization vector perpendicular to the surface of said film. 
     
     
       3. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical material according to claim 1, in which said magnetic mode generating means comprises two laterally spaced electromagnets. 
     
     
       4. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 1, in which said system comprises a head comprising said optical system, said mode magnetic field generating means and semiconductor laser means. 
     
     
       5. A magneto-field recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 4, in which said laser means comprises at least lasers for generating two light beams and including means to vary the intensity of one of the laser beams relative to the intensity of the other of said two beams. 
     
     
       6. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 5, including tracking means responsive to the detection of responsive light by said photo-detecting means to effect tracking by said beams of a record of information on the recording medium. 
     
     
       7. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 4, including a focusing mechanism for variably focusing said optical system under control of said photo-detection means in response to reflected light from a record on said recording medium detected by said photo-detecting means. 
     
     
       8. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 1, including the medium. 
     
     
       9. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material comprising; means for applying two separate light beams on said recording medium for radiating the recording medium with incident radiation at a plurality of irradiated positions; and means including magneto means cooperative in use with said recording medium and the first-mentioned means for effectively using the two light beams for selectively recording information on said recording medium and concurrently reproducing as a readout signal information recorded on said recording medium, or alternately effectively using said light beam for concurrently producing said readout signal and erasing information recorded on said recording medium, or alternately effectively using said light beams for erasing information recorded on said recording medium and concurrently recording information on said recording medium. 
     
     
       10. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 9 in which said magneto means comprises a plurality of means for applying to said recording medium adjacent to some irradiated positions magnetic fields of different coercive values. 
     
     
       11. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material comprising; means for applying two independent light beams on said recording medium with incident radiation at a plurality of irradiated positions; means including magneto means coactive with said recording medium and the first-mentioned means and using the two beams for concurrently effecting any combination of two of three functions comprising the functions of recording information on said recording information, erasing information recorded on said recording medium, and reading out information on said recording medium. 
     
     
       12. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material, according to claim 11, including said recording medium. 
     
     
       13. A magneto-optical recording and reproducing system for recording information on a recording medium made of a magneto-optical recording material according to claim 11, in which the first-mentioned means comprises two lasers, and in which said magneto means comprises means for applying magnetic fields of different coercive values to said some of the irradiated positions on said recording medium.